Tag Archives: Molecular Mechanisms

Question?: Rett Syndrome Research

Chris asks…

Does anyone know why Rett Syndrome girls start off “normal” & then regress?

Okay I’m aware of what Rett Syndrome is & how it works (for the most part anyway) but what has me confused the most is that most of these girls develope normally for about the first 6-18 minths & then start to regress/lose skills they’ve already learned (i.e. talking, walking, eye contact) . I know this is due to a mutation in the MEPc2 gene but why/how is it they can learn things & then lose them later on. I relize the gene is responsible for turning on/off certian protiens but what is making these girls funtion properly in the beginning then? another gene maybe?

admin answers:

To quote a passage from wikipedia:
“The recent studies demonstrating that neurological deficits resulting from loss of MeCP2 can be reversed upon restoration of gene function are quite exciting because they show that neurons that have suffered the consequences of loss of MeCP2 function are poised to regain functionality once MeCP2 is provided gradually and in the correct spatial distribution. This provides hope for restoring neuronal function in patients with RTT. However, the strategy in humans will require providing the critical factors that function downstream of MeCP2 because of the challenges in delivering the correct MeCP2 dosage only to neurons that lack it, given that the slightest perturbation in MeCP2 level is deleterious. Thus, therapeutic strategies necessitate the identification of the molecular mechanisms underlying individual RTT phenotypes and picking out the candidates that can be therapeutically targeted. The next phase of research needs to assess how complete the recovery is. Clearly, lethality, level of activity, and hippocampal plasticity are rescued, but are the animals free of any other RTT symptoms such as social behavior deficits, anxiety, and cognitive impairments? Since postnatal rescue results in viability, it will be important to evaluate if even the subtler phenotypes of RTT and MECP2 disorders are rescued when protein function is restored postnatally. This is particularly important given emerging data about early neonatal experiences and their long-term effects on behavior in adults.”

What I get from that is that the nerves become damaged by the defective gene, resulting in a loss of abilities that have already been learned.

Sorry if you’ve already read this, but this is just about all I could find as far as the reason for the decline period.
Hope this helps!

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A Mechanism To Improve Learning And Memory

Main Category: Psychology / Psychiatry
Also Included In: Alzheimer’s / Dementia;  Autism
Article Date: 22 Feb 2012 – 1:00 PST

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There are a number of drugs and experimental conditions that can block cognitive function and impair learning and memory. However, scientists have recently shown that some drugs can actually improve cognitive function, which may have implications for our understanding of cognitive disorders such as Alzheimer’s disease. The new research is reported 21 February in the open-access journal PLoS Biology. The study, led by Drs. Jose A. Esteban, Shira Knafo and Cesar Venero, is the result of collaboration between researchers from The Centro de Biología Molecular Severo Ochoa and UNED (Spain), the Brain Mind Institute (EPFL, Switzerland) and the Department of Neuroscience and Pharmacology (Faculty of Health Sciences, Denmark).

The human brain contains trillions of neuronal connections, called synapses, whose pattern of activity controls all our cognitive functions. These synaptic connections are dynamic and constantly changing in their strength and properties. This process, known as synaptic plasticity, has been proposed as the cellular basis for learning and memory. Indeed, alterations in synaptic plasticity mechanisms are thought to be responsible for multiple cognitive deficits, such as autism, Alzheimer’s disease and several forms of mental retardation.

The study by Knafo et al. provides new information on the molecular mechanisms of synaptic plasticity, and how this process may be manipulated to improve cognitive performance. They find that synapses can be made more plastic by using a small protein fragment (peptide) derived from a neuronal protein involved in cell-to-cell communication. This peptide (called FGL) initiates a cascade of events inside the neuron that results in the facilitation of synaptic plasticity. Specifically, the authors found that FGL triggers the insertion of new neurotransmitter receptors into synapses in a region of the brain called the hippocampus, which is known to be involved in multiple forms of learning and memory. Importantly, when this peptide was administered to rats, their ability to learn and retain spatial information was enhanced.

Dr. Esteban remarks: “We have known for three decades that synaptic connections are not fixed from birth, but they respond to neuronal activity modifying their strength. Thus, outside stimuli will lead to the potentiation of some synapses and the weakening of others. It is precisely this code of ups and downs what allows the brain to store information and form memories during learning”.

Within this framework, these new findings demonstrate that synaptic plasticity mechanisms can be manipulated pharmacologically in adult animals, with the aim of enhancing cognitive ability. Dr. Knafo adds: “These are basic studies on the molecular and cellular processes that control our cognitive function. Nevertheless, they shed light into potential therapeutic avenues for mental disorders where these mechanisms go awry”.

Article adapted by Medical News Today from original press release. Click ‘references’ tab above for source.
Visit our psychology / psychiatry section for the latest news on this subject. Funding: This work was supported by grants from the Spanish Ministry of Science and Innovation (SAF-2008-04616, SAF-2009-05558-E, CSD-2010-00045, and SAF-2011-24730 to J.A.E; SAF2010-15676 to S.K.; SAF-2009-09129 to C.V.; PI-08/1067 to J.M.S.; SAF-2009-09394 to J.D.F.). In addition, the laboratory of J.A.E. is funded from Fundación Ramón Areces and Institut de France-NRJ; the laboratory of J.D.F. from Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED, CB06/05/0066) and Fundación CIEN; the laboratory of C.S. from the EU (FP7-HEALTH-F2M-2008-201600, MemStick) and the Swiss National Science Foundation (310000-120791). S.K. is the recipient of a “Ramón y Cajal” contract from the Spanish Ministry of Science and Innovation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: I have read the journal’s policy and have the following conflicts: E. Bock and V. Berezin are shareholders of ENKAM Pharmaceuticals A/S, which owns the FGL peptide (less than 0.01% shares each). Nevertheless, this does not alter our adherence to all the PLoS Biology policies on sharing data and materials.
Citation: Knafo S, Venero C, Sa´nchez-Puelles C, Pereda-Pere´z I, Franco A, et al. (2012) Facilitation of AMPA Receptor Synaptic Delivery as a Molecular Mechanism for Cognitive Enhancement. PLoS Biol 10(2): e1001262. doi:10.1371/journal.pbio.1001262
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